T-square



(No Model.)

F. BENZINGER & H. E. GfRABAU.

T SQUARE 910.418,969. Patented Jan.7,1890.

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UNITED STATES PATENT OFFICE. x

FREDERICK BENZINGER, OF NEV YORK, N. Y., AND HANS EDGAR GRABAU, OF HOBOKEN, NEW JERSEY.

T-SQUARE.

SPECIFICATION forming part of I etters` Patent No. 418,969, dated January '7, 1890.

Application led October 22, 1889. Serial No. 327,807. (No model.)

To @ZZ whom it may concern:

Be it known that we, FREDERICK BENZIN- GER, of New York, county and State of New York, a citizen of the United States, and HANs EDGAR GRABAU, of Hoboken, county of Hudson, and State of New Jersey, a citizen of the Empire of Germany, have invented certain new and useful Improvements in T-Squares, of which the following is a specification.

This invention relates to improvements in Tsquares usually used by draftsmen.

The object of our invention is to provide a Tsquare which is so constructed that the blade can be set and locked at different angles to the head, or can be so adjusted that it can be turned freely on the head.

In the accompanying drawings, Figure l is a top view of our improved T-square, the blade being held in position at an angle of ninety degrees to the edge of the head,parts being broken out. Fig. 2 is a similar view, showing the blade released, so that it can be turned on the head, parts being broken out. Fig. 3 is a vertical section on the line 3 3, Fig. l. Fig. 4 is a face view of the under side of the circular plate on the end of the blade. Fig. 5 is a detail plan of the sliding catch, the handle being shown in section. Fig. 6 is a bottom View of the thumb-nut. Fig. 7 is a side view of the same.

Similar letters of v reference indicate corresponding parts.

The head A, which may have any desired shape, is provided with a circular recess B, at the edge of which a circular rail C is fixed, which is provided with apertures a, Z), and c, which are so arranged that lines drawn through the same to the center of the circular recess B form angles of forty-five degrees. A screw-pivot D is secured at the center of the circular recess B and projects from the upper surface of the head A. On one end of the blade E a circular disk F is securely iixed, which is of such size that it iits snugly within the circular recess B and can rotate on the rail C. Said disk F is provided with a slot F extending from the central aperture of the disk F to the rim, and in the same the sliding latch or bolt G is arranged, which is provided at one end with a head H, adapted to pass into the notches a, ZJ, and c of the rail C, and

Aof the disk F.

at its opposite end said lat-ch or bolt G is provided with a hook J, the shank of which projects upward. A knob K is passed through a slot L in the blade E and is connected with 5 5 the sliding bolt or catch G. A spring M has one end fastened on the disk F, and the other end bears against the inner end of the sliding bolt G and presses said bolt toward the rim The thumb-nut N, which can 6o be screwed on the pivot-screw D, is provided on its lower end with a neck O, having an aperture or notch P. A washer R is placed between the bottom edge of the thumb-nut N and the upper surface of the blade E.

The blade E can be locked in position at right angles to the edge of the head A, or at an angle of forty-five degrees, as shown by the dotted lines in Fig. l.

The bolt or latch G is pressed by means of 7o its knob K in the direction toward the pivotpin D, so as to move the head H on said latch out of one of the notches a, b, or c, so as to permit swinging the blade E on the head A@ As soon as said head of the latch has been withdrawn from the notches and the blade E turned slightly from the head the latch-knob is released, so as to permit the spring M to press the latch-head against the inner edge of the rail C. Vhenthe latch arrives at anotch in the rail C, it snaps into the same, locking the blade in position.

'When it is desired to turn the blade freely on its pivot, the latch must be withdrawn and locked in position when withdrawn. To accomplish this the latch is pressed inward, so that its hook K rests against the outer surface of the neck O on the thumb-nut N, and then said nut is turned, and when the hook J arrives at the notch P in the neck O it passes into the same, and if the nut is then turned it will engage said hook and keep the latch G withdrawn, as shown, for example, in Fig. 2. The blade can then be swung in any position on the head and can be locked in place by 95 turning the thumb-nut N, care being taken to keep the knob K on the latch pressed inward while thus turning the thumb-nut, so a-s to prevent the hook J on the inner end of the latch from becoming disengaged from the neck on the thumb-nut.

Having thus described our invention, we

IOO

head having a circular recess and a pivotscreW at the center of said recess, of a blade and a circular disk to Which said blade is secured, a sliding spring-latch on said blade, a hook on the rear end of said latch, and a thumb-nutadapted to be screwed on the pivotscreW in the head and .provided at its lower end with a neck havinga notch thron gh which the said hook can pass, substantially as set forth;

3. In a T-square, the combination, with a 'head and a pivot-screw projecting upward from the saine, of a blade mounted to turn on said pivot-screw, a sliding latch on said blade, which latch can engage notches on the head, and means for locking said latch in place when Withdrawn, so as not to engage the notches, substantiall57 as set forth.

In testimony that we claim the foregoing as our invention we have signed our names in presence of two subscribing witnesses.

FRED. BENZINGER HANS EDGAR GRABAU.

Witnesses:

OSCAR F. GUNZ, W. REIMHERR. 

